Bathypurpurinopsis stantoni, Kiel & Campbell & Elder & Little, 2008

Kiel, Steffen, Campbell, Kathleen A., Elder, William P. & Little, Crispin T. S., 2008, Jurassic and Cretaceous gastropods from hydrocarbon seeps in forearc basin and accretionary prism settings, California, Acta Palaeontologica Polonica 53 (4), pp. 679-703 : 693-694

Bathypurpurinopsis stantoni sp. nov.

Fig. 8G–L .

Etymology: After Timothy William Stanton (1860–1953) who pioneered detailed taxonomic studies of invertebrate fossils from the Great Valley “white limestones”.

Type material: Holotype: CAS 70402 , large specimen with three whorls and a distinctive basal fold; paratypes: two specimens from the type locality ( UCMP 555102 , 555103 ) and four additional specimens from the type locality.

Type locality: Cold Fork of Cottonwood Creek , Tehama County, California, USA (site 1) .

Type horizon: Albian ( Lower Cretaceous ) seep carbonates, Lodoga Formation , Great Valley Group .

Diagnosis.—As for genus.

Description.—Shell moderately high spired, fusiform to littoriniform, with at least three whorls and incised suture, apical angle 38°; whorls convex, sculptured by fine, equally sized spiral threads, interspaces slightly wider than threads; growth lines fine, sinuous, slightly prosocyrt in upper half of whorl, slightly opisthocyrt in lower half; basal margin strongly constricted with a prominent siphonal fold below, growth lines on fold very strongly opisthocyrt, suggestive of deep siphonal notch; aperture broadly oval.

Stratigraphic and geographic range.—Known only from the type locality, Lodoga Formation, Great Valley Group; Albian (Lower Cretaceous).

Species of uncertain affinity

“ Cerithium ” sp.

Fig. 9A .

1895 Cerithium sp. ; Stanton 1895: 71.

Material.—The specimen described by Stanton ( USNM 23081) from Cold Fork of Cottonwood Creek (site 1). Description.—Two or three straight−sided whorls preserved, sculpture of nodular subsutural cord, another cord with two rows of tubercles near base; basal margin sharp, base flat, columellar and parietal lip of aperture smooth and strongly convex, suggestive of round aperture. Height 3.5 mm.

Discussion.—The described characters can be found in the Cretaceous campanilid Metacerithium (cf. Kiel 2006a) and in modern cerithiopsids (cf. Marshall 1978). The specimen is figured here because it was collected from presumed seep carbonates at Cold Fork of Cottonwood Creek ( Stanton 1895) and because Stanton did not figure it.

Stratigraphic and geographic range.—Albian (Lower Cretaceous), seep carbonates at Cold Fork of Cottonwood Creek, Lodoga Formation, Great Valley Group, California, USA.

Fusiform gastropod

Fig. 9B .

Material.— One specimen from Rocky Creek (site 7) .

Description.—Fusiform shell with two whorls preserved; suture incised, deep; whorls slightly convex, first whorl apparently smooth, on last whorl sinuous growth lines thickened to form sinuous, axial ribs; conspicuous ridge below suture that becomes tuberculate on last whorl where it is crossed by axial ribs; nine to ten spiral cords develop on lower third of last whorl, these cords are subequally spaced, interspaces as wide as cords, and with rounded crests; growth lines sinuous: opisthocyrt notch below suture, almost straight on whorl’s flanks, gently sloping backwards on lower third of whorl. The shell is 9 mm high.

Discussion.—At first glance, this specimen resembles some neogastropods from the Upper Cretaceous Ripley Formation of the US Gulf Coast plains, especially Ornopsis or Bellifusus (see Sohl 1964). However, the basal part of the specimen is not preserved or visible, hence the presence of a siphon is uncertain. The specimen may actually have just a siphonal notch in its aperture like cerithioids or littorinids. It could also be a Paskentana .

Stratigraphic and geographic range.—Known only from the Rocky Creek site, Valanginian (Lower Cretaceous), Crack Canyon formation, Great Valley Group, California, USA.

High spired gastropod

Fig. 9C .

Material.— Two specimens from W Berryessa (site 11).

Description.—Two−and−a−half whorls preserved; shell slen− der, high spired, whorls convex, suture finely incised; last whorl with nine spiral ribs that frequently show short, forward−pointing, hollow spines, ribs with rounded crests and subequally spaced, with interspaces about one to two times the width of ribs; growth lines narrowly spaced and strongly opisthocyrt.

Remarks.—This type of spiral sculpture without any obvious axial elements is quite unusual for cerithiform gastropods of this age. The poor preservation precludes a more precise classification of this species.

Stratigraphic and geographic range.—Known only from the W Berryessa, Early Cretaceous (probably Valanginian), Great Valley Group, California, USA.

Figures

Fig. 8. Gastropods of uncertain taxonomic position, Atresius liratus Gabb, 1869 and Bathypurpurinopsis stantoni sp. nov., from Early Cretaceous seep carbonates in California, USA. A–F. Atresius liratus. A. Specimen (CAS 70395) with broad shoulder, from Rocky Creek (Valanginian; site 7). B. Specimen (CAS 70396) from Rocky Creek, note fine spiral sculpture on shoulder. C. Specimen (CAS 70397) with strong axial ribs, from Rocky Creek. D. Large specimen (CAS 70398) with rounded basal margin, from Rocky Creek. E. Specimen (USNM 23075a) illustrated by Stanton (1895: pl. 11: 6). F. Another specimen (USNM 23075b) from Stanton’s lot with fewer but stronger spirals, and a more angular basal margin. G–L. Bathypurpurinopsis stantoni, from Cold Fork of Cottonwood Creek (Albian; site 1). G. Specimen (CAS 70399) with thin apertural fold and preserved siphonal column. H. Specimen (CAS 70400) with excavated aperture. I. Specimen (UCMP 555102) showing fine spiral sculpture and sinuous growth lines. J. Specimen (CAS 70401) with well−developed apertural fold, note the indented shell on the left. K. Holotype (CAS 70402). L. Smooth specimen (UCMP 555103) with excavated aperture.

Fig. 9. Gastropods of uncertain affinities from Early Cretaceous seep carbonates in California, USA. A. Stanton’s (1895) “Cerithium” sp. (USNM 23081) from Cold Fork of Cottonwood Creek (Albian; site 1), image taken with light microscope (A1) and with SEM (specimen uncoated, A2). B. Fusiform gastropod (CAS 70403) from Rocky Creek (Valanginian; site 7). C. High−spired gastropod (CAS 70404) from W Berryessa (probably Valanginian; site 11).